Various substances, particularly medicines, need to be used and in particular inhaled in the form of a fine powder. A difficulty then arises of combining simplicity for the device, effectiveness, in particular accuracy and dispersion of the dose delivered, and safety, in particular hygiene and asepsis, etc. It therefore appears advantageous, a priori, to package such substances in single-dose capsules that then need to be opened, e.g. by being cut or perforated, prior to having their contents entrained in the inhaled flow of air. This difficult operation has already been performed in numerous different manners: thus, to expel the substance, proposals have been made to use: gravity or centrifuging; vibration or suction; or sweeping, either directly with the main flow, or else using flow induced by a venturi.
However, prior devices do not enable the creation or emission of the powder-carrying flow to be synchronized quickly with inhalation. In addition, those devices need to be refilled frequently, which makes them laborious to use.